written by George Dvorznak

During our recent history talk about the Vietnam War, I mentioned how the Ho Chi Minh Trail emptied out north and west of Saigon in a place called Cu Chi. Cu Chi became one of the most important enemy strongholds of the war, where the vast amounts of materials and weaponry were stored and distributed.

That’s why the US Army built one of its largest bases in all of Vietnam right in Cu Chi and 1966 stationed the 25^th Infantry Division there. Unlike the rest of the Army, the 25th Division was trained for jungle and guerrilla warfare. But they weren’t prepared for tunnels.

Soon after setting up the Cu Chi Base Camp, US personnel began noticing damaged helicopter motors, stolen food, and even soldiers being killed in their cots. Saboteurs managed to wreck Chinooks and harm service members without even breaching the perimeter.

Turns out, the entire base was undermined by tunnels and trap doors.

The Cu Chi Tunnels stretched over 250 miles from the western outskirts of Saigon to the Cambodia border. The tunnels had bunkrooms, hospital rooms, kitchens, and even a few classrooms. And there were escape hatches and trap doors everywhere.

According to the Journal of Social Science, the unique soil of Cu Chi, along with the low water table, made tunnels easy to dig and hard to destroy. The iron in the soil, combined with other elements, meant you could easily dig it by hand. But when exposed to air, that soil became as strong as concrete. Also, the soil breathed, allowing a measure of oxygen to come through, even though it was otherwise impermeable.

Tunnel work was some of the grimmest and most dangerous assignments a GI could pull. “Tunnel Rats” entered deep holes riddled with of booby traps, boxes of scorpions and snakes, and, of course, enemy guerrillas.

Vietnam Veteran George Dvorznak viewed our program on the Cu Chi Tunnels and sent this first-hand glimpse of history as the Army struggled with the problem of how to clear the tunnels.

I graduated from the University of Pittsburgh in April of 1965 with a degree in Mechanical Engineering and a commission as an Ordnance Second Lieutenant.

I had a year after graduation as a civilian so I could get a hernia operation and pass the Army physical.  So I went to work as a civilian engineer at the Bureau of Mines near South Park, PA.  I’d worked there as a student trainee while I went to college to earn tuition money.

This was in April 1965 and the Army already knew that tunnels at Cu Chi would be a problem.

The Bureau had a reputation for explosion research, and a tunnel is just a little mine.  The solution to destroying the tunnels was to get enough explosive material into them, initiate the explosion, and see the results.

Sounds like a simple solution. But it wasn’t.

We started out by building some test tunnels using a technique called “cut and cover.”

We dug a four-foot deep trench with a backhoe, then covered the trench with corrugated steel sheets, and covered the sheets with the excavated dirt.

The result wasn’t a duplicate of the Cu Chi Tunnels, but it was a good start. And what did we know of Cu Chi, anyway?

We proceeded to fill it with explosive stuff.

First, we tried an industrial gas called MAPP which was used for burning steel, like an oxy-acetylene torch.

It blew up, but MAPP wouldn’t flow down the tunnel for any distance.

Then, we tried blowing powdered aluminum into the tunnel with a backpack blower.

Same problem.

So, in desperation and some frustration, we initiated a tunnel explosion with an explosive called PETN.  It looks just like chalk. A very satisfying explosion resulted, but not extensive enough to do any real damage because of the problem of getting the explosive material to flow throughout the tunnel.

One unintended consequence was that sheets of corrugated steel went flying thru the air, and we all scrambled under trucks to avoid getting sliced up by the sheets when they came down.

We never did develop a satisfactory way to blow up our simulated Ci Chi Tunnel.  Maybe we’d have better luck today with the use of robots, fiber optics, and night vision cameras. Without those, the Army did what it always does: used whatever was at hand.

In this case, that meant brave young men carrying .45 pistols in one hand and a flashlight in the other.

These Tunnel Rats did the job we couldn’t engineer at the Bureau of Mines. Like in Okinawa and Iwo Jima, where flame throwers and bulldozers did the dirty work, destroying tunnels in Cu Chi required brute force and brave troops.